All documents discussed herein, and all documents in provisional application Ser. No. 60/175,548 filed Jan. 11, 1999, are hereby incorporated by reference.
Insect control in the United States, for example, mosquito control, is almost always done for the control of annoying biting insects and for disease prevention. The control and reduction of mosquito populations is done by either larviciding (killing larvae in the water in which they breed) or adult control using various insecticides.
Substantial efforts have been expended by a wide variety of entities in attempting to develop highly effective pesticides, particularly insecticides, which are capable of eradicating or controlling insects which destroy ornamental and agricultural plants, crops, and trees, or which attack, harm, or annoy humans and animals. Particularly bothersome to humans and animals are blood-sucking insects, such as mosquitoes, ticks, fleas, and lice. These insects are annoying as well as potentially harmful due to the potential transmission of diseases. It is not only for the suppression of disease that insect control is needed. There is a perennial call for abatement of the nuisance of insects, such as mosquitoes, which make unprotected outdoor activities all but impossible at certain seasons of the year in many parts of the world. Although substantial need has existed in the industry for products which control or eradicate these insects and for systems to effectively prepare these products for application, prior attempts have failed to provide systems that are optimized for the preparation of particular insecticidal formulations.
A number of injector devices have been used for dispensing chemical substances for a variety of applications. Such devices include the non-electric proportional injection systems, such as the DOSMATIC.RTM. injector available commercially from Dosatron International, Rue Pascal-BP-6, 33370 Tresse (Bordeaux), France, which operates without electricity by using water pressure as the power source. On its way through such a system, the water pressure activates the dispenser which takes up the required percentage of concentrate directly from the container and injects the concentrate into a fluid stream for dilution. These units are precise and relatively simple and have been used in a wide range of applications, including irrigation, livestock hygiene and crop spraying.
Other devices for mixing concentrated insecticides with a carrier, such as water, include the use of a variety of pumps. Pumps, including positive displacement pumps, vane pumps, rotary lobe pumps, or any type of metering pump, can be used to add a concentrated insecticidal formulation with a carrier. These pumps can be configured to pump a concentrated insecticide into a carrier such as oil or water. Alternatively, these pumps can be used to inject the concentrated insecticidal formulation into a water stream or a carrier stream, thereby diluting the concentrated insecticide when it mixes with the fluid stream.
Space spray insecticides are generally dispersed as ultra low volume (ULV) space treatments or fogs to kills adult mosquitoes. An insecticide is diluted and atomized by a ULV fogging machine. The insecticide would then be released from the ground or from the air. Air currents would carry the droplets downwind of the application equipment. The droplets would collide with the insects, coating the insect with a lethal dose of the active ingredient. A system for dispersing an insecticide in this manner is described in U.S. Pat. No. 5,248,448, entitled Aerosol Generator Apparatus with Control and Recording, and is hereby incorporated by reference.
Space spray aerosol insecticides, such as mosquito adulticides, are generally diluted with oil because this was the only carrier that distributed the insecticide accurately and evenly over a wide range of conditions. However, there are a number of disadvantages and problems associated with oil-based carriers. These include potential storage liability, environmental concerns, inconvenience and additional cost.
Water dilutable insecticides include formulations such as the FFAST.TM. (an acronym for Film Forming Aqueous Spray Technology) insecticide formulations described in this application, which allow for the use of water as a diluent. U.S. Pat. Nos. 5,466,458 and 5,527,823 describe insecticidal formulations suitable for dilution with water to form a space spray aerosol. These patents are hereby incorporated by reference.
It is generally less expensive and more desirable to have the option of using a water-based product. However, at ambient temperatures, conventional water-based sprays tend to evaporate quickly and fail to deliver the insecticide to the target insects or pests efficiently. To overcome this problem in the past, dispersing insecticides in water required the creation of large droplets. However, these large droplets did not drift efficiently and did not reach the target at all.
A formulation, such as the FFAST.TM. formulation, using long chain alcohol molecules to form a protective film around each droplet of insecticide as it leaves the nozzle of the sprayer, allows for the formation of droplets that do not evaporate too quickly and that efficiently deliver the insecticide to the target insect. The incorporation of long chain alcohols into the formulation provides a means of coating the individual droplets of insecticides when mixed with water so as to control the rate of evaporation. This film retards the evaporation of the droplets and they maintain the desired optimum size.
The FFAST.TM. insecticide formulations therefore offer the benefits of using water as a diluent with the performance of oil-based dilution. For example, AQUA-RESLIN.RTM. insecticide is a concentrated formulation of a water dilutable mosquito adulticide that has as its active ingredient the pyrethroid permethrin, synergized with piperonyl butoxide, and is formulated in such a way as to be diluted with water, as opposed to oils, for subsequent application. By using the process and injector system of the present invention, the end user has the economic benefit of being able to purchase a concentrated insecticide that can be easily diluted with water and has the benefit of limiting the risks normally associated with worker exposure to the oils previously used to dilute an insecticide.
A specific injector system that could mix the concentrated insecticide, accurately dilute the insecticide with water, and dispense water diluted insecticides has not been available. Further, a process for mixing, diluting and dispensing water soluble formulations of insecticides using an injector system as an ultra low volume (ULV) space spray aerosol for the control of mosquitoes has heretofore not been available.
Accordingly, a need remains for a process for preparing insecticides that can be diluted with water and for an injector system which can mix the concentrated insecticide, accurately dilute with water, and dispense the water diluted insecticidal formulation into application equipment, thereby eliminating the problems associated with the use of oil as a diluent or carrier of the insecticide. It is to this injector system and process for preparing an insecticide that the present invention is primarily directed.